Strain-specific proteome responses of Pseudomonas aeruginosa to biofilm-associated growth and to calcium

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen that forms biofilms on mucous plugs in the lungs of cystic fibrosis (CF) patients, resulting in chronic infections. Pulmonary P. aeruginosa isolates often display a mucoid (alginate-producing) phenotype, whereas non-mucoid strains are generally associated with acute infections. We characterized the cytosolic proteomes of biofilm-associated and planktonic forms of a CF pulmonary isolate, P. aeruginosa FRD1, and a non-mucoid strain, PAO1. Since Ca 2+ metabolism is altered in CF pulmonary fluids, we also analysed the effect of Ca 2+ on the proteome responses of these strains. Both strains altered the abundances of 40-60 % of their proteins in response to biofilm growth and/or [Ca 2+ ].Differentially expressed proteins clustered into 12 groups, based on their abundance profiles. From these clusters, 146 proteins were identified by using MALDI-TOF/TOF mass spectrometry. Similarities as well as strain-specific differences were observed. Both strains altered the production of proteins involved in iron acquisition, pyocyanin biosynthesis, quinolone signalling and nitrogen metabolism, proteases, and proteins involved in oxidative and general stress responses. Individual proteins from these classes were highly represented in the biofilm proteomes of both strains. Strain-specific differences concerned the proteins within these functional groups, particularly for enzymes involved in iron acquisition and polysaccharide metabolism, and proteases. The results demonstrate that a mucoid CF isolate of P. aeruginosa responds to biofilm-associated growth and [Ca 2+ ] in a fashion similar to strain PAO1, but that strain-specific differences may allow this CF isolate to successfully colonize the pulmonary environment.

Heterogeneity in Pseudomonas aeruginosa Biofilms Includes Expression of Ribosome Hibernation Factors in the Antibiotic-Tolerant Subpopulation and Hypoxia-Induced Stress Response in the Metabolically Active Population

“…4) (see Table S3 in the supplemental material). Our previous proteomics study using whole biofilms showed high protein amounts of chaperones and proteases generally associated with the heat shock response (50). The transcriptomics results here are consistent with those of the proteomics study and also indicate that proteases and chaperones regulated by RpoH and misfolded protein stress are highly induced at the top of these biofilms.…”

“…The two most abundant usp mRNA transcripts are the uspK (PA3309) and uspN (PA4352) genes. Proteomic analysis of whole biofilms showed that UspK and UspN were abundant in P. aeruginosa biofilms (50). The previous proteomics study comparing two different P. aeruginosa strains in a flow-through biofilm system demonstrated that uspK and uspN induction and stress response may be a general feature of P. aeruginosa biofilms.…”

“…For example, the antibiotics tobramycin and ciprofloxacin preferentially kill cells at the periphery of the biofilms, while other chemical agents, including gallium, sodium dodecyl sulfate, and colistin, are effective against cells in the cluster centers. In order to characterize physiological features of biofilm bacteria and to gain a better understanding of mechanisms for enhanced antibiotic resistances, transcriptomic and proteomic profiles of microbial biofilms have been determined and compared to the profiles of planktonic cells (21,28,43,50,58,68,73). For these global approaches, it is often necessary to harvest the entire biofilm community to obtain sufficient RNA or protein for analysis.…”

Analysis of the Pseudomonas putida CA-3 proteome during growth on styrene under nitrogen-limiting and non-limiting conditions

“…Bacterioferritins whose expression levels vary as a function of environmental and intracellular iron levels have been identified in P. putida KT2440 (Chen et al, 2009). Similarly, bacterioferritins are highly expressed in biofilms of P. aeruginosa (Patrauchan et al, 2007), but they have not been identified as being upregulated under N-limited growth conditions. Fig.…”

Characterization of a biofilm membrane reactor and its prospects for fine chemical synthesis

“…During some stages of biofilm development, as much as 50% of the proteome can be differentially produced compared with the same cells growing in planktonic culture (Patrauchan et al, 2007;Sauer et al, 2002).…”